This study evaluates the effects of an intervention aimed at improving representational flexibility in linear-function problems. Forty-nine students aged 13-16 participated in the study. A pretest-intervention-posttest design with an experimental and control group was used. At pretest, both groups solved a choice test, where they could freely…

Reviews the literature on Bradford's law (i.e., an empirical relationship describing the distribution of scholarly articles in relevant journals). A model for the distribution of articles, based on random partitioning, is presented; and a mathematical formulation for a law of scattering is derived. The relationship of the model to Bradford's law…

Investigates the relationships between the parameters of the Simon-Yule model and the shapes of three bibliometric distributions: Lotka's Law of Scientific Productivity; Bradford's Law of Bibliometric Scattering; and Zipf's Law of Word Frequency. The results indicate that the probability of a new entry determines the characteristics of all three…

Describes three models for probabilistic indexing, all based on the Darmstadt automatic indexing approach, and presents experimental evaluation results for each. The discussion covers the improved retrieval effectiveness of probabilistic indexing over binary indexing, and suggestions for using this automatic indexing method with free text terms.…

Examines the problem of aging of books in university libraries and presents a mathematical model of the aging process. Indexes for the aging time limit, over-age book rate, and aging rate are suggested; use of the mean unit price is considered; and countermeasures for control of the aging process are proposed. (four references) (MES)